Volume 56, Issue 6 - Special Issue: Reliably Secure Software Systems / Heiko Mantel

We present a uniform, top-down design method for security type systems applied to a parallel while-language. The method takes the following route: from a notion of end-to-end security via a collection of stronger notions of anytime security targeting compositionality to a matching collection of type-system-like syntactic criteria. This method has emerged by distilling and unifying security type system results from the literature while formalizing them in a proof assistant. Unlike in our previous papers on this topic, here we focus entirely on high-level ideas instead of technical proof details.

The family of temporal logics has recently been extended with logics for the specification of hyperproperties, such as noninterference or observational determinism. Hyperproperties relate multiple computation paths of a system by requiring that they satisfy a certain relationship, such as an identical valuation of the low-security outputs. Unlike classic temporal logics like LTL or CTL*, which refer to one computation path at a time, temporal logics for hyperproperties like HyperLTL and HyperCTL* can express such relationships by explicitly quantifying over multiple computation paths simultaneously. In this paper, we study the extended spectrum of temporal logics by relating the new logics to the linear-branching spectrum of process equivalences.

JOANA is a tool for software security analysis, checking up to 100 kLOC of full multi-threaded Java. JOANA is based on sophisticated program analysis techniques and thus very precise. It includes a new algorithm guaranteeing probabilistic noninterference, named RLSOD. JOANA needs few annotations and has a nice GUI. The tool is open source and was applied in several case studies. The article presents an overview of JOANA and its underlying technology.

The functionality of modern smartphones can easily be enriched by a huge number of available apps. Studies have shown that many of these apps leak private information of their users to third parties. In this article, we demonstrate how a user can ensure that the apps he installs keep his private information confidential. By means of a concrete example, we show how an informal confidentiality requirement can be formalized in the specification language RIFL and how this requirement can be verified in the app store Cassandra using the RSCP security analyser. In particular, we demonstrate how Cassandra integrates the information-flow analysis by the RSCP security analyser into the installation process of an app from the perspective of a user.

Workflow management plays an important role in analyzing and automating business processes. Security requirements in workflow management systems are typically mapped to (role-based) access control configurations. This paper focuses on information flow control, taking into account implicit information leaks. The presented approach operates on a specification level in which no executable program is available yet. We illustrate the modeling of a workflow management system as a composition of state-event systems, each representing one of the activities of the workflow. This facilitates distributed deployment and eases verification by splitting up the verification of the overall system into verification of the individual components. Confidentiality requirements are modeled in terms of information flow predicates using the MAKS framework and verified following existing decomposition methodologies, which are adapted for open systems with ongoing user interaction. We discuss the interaction with other security requirements, notably separation of duty.

Systems for electronic voting (e-voting systems), including systems for voting over the Internet and systems for voting in a voting booth, have been employed in many countries. However, most of the systems used in practice today do not provide a sufficient level of security. For example, programming errors and malicious behavior resulting in the loss of votes and incorrect election outcomes easily go undetected. In fact, numerous problems with e-voting systems have been reported in various countries. Therefore, in recent years modern e-voting systems have been designed that, among others, allow voters to check that their votes were counted correctly, even if voting machines and servers have programming errors or are outright malicious. In this paper, after a brief discussion of the problems of today's e-voting systems, we explain fundamental security properties modern e-voting systems should provide, including the above mentioned so-called verifiability property, and present a simple e-voting system to illustrate some of these properties. One important goal of our work is to provide security guarantees of such systems not only for abstract mathematical/cryptographic models of the systems but for the implementation of the systems directly. This requires us to combine various techniques and tools from security/cryptography, program analysis, and verification.

Most networks in use today, most prominently the Internet, follow a design philosophy which aims to support a broad range of applications. This comes to a limit when the combination of application and environment poses increasing challenges with respect to scarce resources (like bandwidth, latency or energy). It also fails if the challenges stem from application requirements that are violated by core network protocols, like, for instance, anonymity requirements in a network using unique addresses. This observation motivates an overarching perspective on the design of network protocols in such cases, which takes the interplay between network and application explicitly into consideration – a challenge which is tackled for several application areas in my research group.

The World Wide Web Consortium (W3C) develops a wide range of standards for data processing on the Web. Prominent examples are RDF, SPARQL, XML, XPath, XQuery, and XSLT. Since these standards are widely used, they bring many interesting challenges for researchers. During the development of these standards, the W3C often works under a rather tight time schedule and does not always have all the cards on the table when design decisions need to be made. This is a situation in which research and practice can greatly benefit from each other. The W3C continuously releases drafts of the standards which researchers can investigate. Researchers can inform the W3C of their results and, conversely, the W3C can give the opportunity to immediately incorporate research results into practice.

XML Encryption and XML Signature describe how to apply encryption and signing algorithms to XML documents. These specifications are implemented in a wide range of systems and frameworks processing sensitive data, including banking, eGovernment, eCommerce, military, and eHealth infrastructures. The article presents practical and highly critical attacks which allow to forge signed XML documents or reveal contents of encrypted XML data.